Molecular structure and vibrational spectra of spin-crossover complexes in solution and colloidal media: resonance Raman and time-resolved resonance Raman studies.

The spin-crossover system [Fe(btpa)](PF(6))(2) (btpa = N,N,N',N'-tetrakis(2-pyridylmethyl)-6,6'-bis(aminomethyl)-2,2'-bipyridine) and the predominantly low-spin species [Fe(b(bdpa))](PF(6))(2) ((b(bdpa) = N,N'-bis(benzyl)-N,N'-bis(2-pyridylmethyl)-6,6'-bis(aminomethyl)-2,2'-bipyridine) have been characterized by means of X-ray diffraction. The unit cell of [Fe(btpa)](PF(6))(2) contains two crystallographically independent molecules revealing octahedral low-spin and quasi-seven-coordinated high-spin structures. The unit cell of [Fe(b(bdpa))](PF(6))(2) contains two crystallographically independent molecules one of which corresponds to a low-spin structure, while the other reveals a disordering.